The wood in whisky

A phenomenon called maturation. PATRICK LECLEZIO bows respectfully but unflinchingly to one of the great forces in whisky.

First published in Prestige Magazine (August 2016 edition).

The use of wood in crafting whisky is enormously important. Many years ago – almost all the players seem to have their own quaint, romantic story about how it occurred – someone put their spirits into an oak cask, ostensibly for storage or transport, left it for longer than intended, and realised that the resultant, conditioned liquid had been considerably enhanced. I can only imagine the joy of that discovery, the whisky equivalent of fire, or the wheel, or penicillin (or maybe that’s me imagining what I would say after appropriately celebrating the discovery). Anyhow, in the aftermath of this happy accident (or these happy accidents, if we’re to give everyone the benefit of the doubt) laying spirits in wood gradually became a deliberate practice, utilised across the board. It is now of such importance that the makers of fine spirits, and other drinks too (wines and fortified wines in particular), dedicate massive resources to what is known as maturation. In asserting and validating the extent of its influence I’m going to delve into some the critical factors, but I also want to counter myself with a cautionary voice, because maturation is the one issue in whisky that tends to be over-aggrandised – so I’ll attempt to debunk the glib statements that are sometimes used to stress its importance, but that often misrepresent and mislead.

I’ve repeatedly been told that the most important influence on the flavour of a whisky is its maturation, or, similarly, that maturation contributes 60% (or 70%, or 80% – depends to whom you’re listening) of the flavour of a whisky…and I’ve probably passed on these same suppositions myself. No longer, or at least, not in these terms. I have no problem with the direction of the sentiment (there’s no doubting that maturation is important, enormously so, as I’ve already said and will say again, and in many or even most cases of majority importance), but I find it tenuous to reduce it to a fixed, universal, and absolute point. Firstly the effect of maturation on different whiskies is variable: most obviously because of its duration, the weightings of its input into a 3YO and a 25YO will be dramatically different, but also because wood is a natural substance, and therefore not consistent in its impacts, and further because the relative scale of other influences will also vary. In the Ardbeg 10YO for instance I could make the (not unreasonable) contention that it is peat smoke and not maturation that commands the single biggest impression in the flavour. Secondly, flavour is subject to interpretation – it simply can’t be factually referenced in quantitative terms (when this is done in scoring it’s an opinion), or even in definitive terms. I may be predominantly captivated by the biscuit notes in Maker’s Mark, which I attribute to the wheat in the mashbill, but someone else, sitting drinking the identical whisky opposite me, may be more captivated by the sweet vanilla derived from the casks. The reason I’m labouring this point is that flavour is suggestive. If you believe that maturation is the be-all, end-all, that’s often what it will be, perhaps to your detriment. During a business trip with two seasoned industry professionals we were served a cognac which we were told was a Scotch whisky. We proceeded to debate amongst ourselves whether it was a blend or a single malt (I went for single malt, at least I got the copper distillation right). In retrospect (blushes notwithstanding) I knew I had identified something funky, but I had simply ruled it out of my mind before even picking up the glass that this was anything other than whisky. Question assumptions, about this and about anything else really (life rule).

When we talk about maturation, we effectively refer, in very simplistic terms, to the process over time where a liquid resting in a cask absorbs (and relinquishes) certain characteristics, primarily from (and to) the cask itself, and to a lesser degree from the environment in which the cask is accommodated, which permeates as the cask expands and contracts (breathes) with temperature fluctuations, and where the liquid further evolves as the result of chemical reactions between its component compounds and those being absorbed. The cask itself plays the pivotal role, both intrinsically, by contributing the natural elements of the wood from which it’s made, and by passing on “second-hand” flavours that it has absorbed in its previous maturations, typically of bourbon or sherry, but increasingly of other drinks as well. I recently worked my way through a bottle of the Glenfiddich 21YO (“raised in Scotland, roused by the Caribbean”…classic), finished in rum casks, with the molasses underpinning that spirit startlingly and deliciously evident in the final liquid. Glenmorangie has just released Milsean, a whisky finished (extra matured in their parlance) in Portuguese red wine barriques. Michel Couvreur, a brand with which I was previously associated, produces Spiral, which is finished (double matured might be more apt given the duration) in Jura vin de paille casks and which is one of the outstanding whiskies of my experience. William Grant, and now Jameson (and possibly others), make whisky finished in ale casks. And on it goes. This aspect of maturation has created a model where the possibilities for flavour diversity are almost endless. It is the sexy face of maturation. Ex-sherry, ex-bourbon! Oloroso, Pedro Ximinez, manzanilla! Port, sauternes! And whilst it’s undeniably interesting and alluring it’s important not to forget that much of the body of the whisky comes from the wood itself.

The wood in whisky is the mighty oak – as is the case for most spirits. There are indigenous Brazilian trees that are used for maturing cachaça, the odd, old, arbitrary chestnut cask has turned up here and there in Scotland, and I’ve read of an American whiskey using maple for finishing, but these are strictly exceptions. Somehow, out of all the trees in all the world, it’s curiously only oak that works properly (mighty indeed!), and furthermore only oak that has been grown in the right climate and conditions. The attempt to grow Quercus Alba (American white oak) in South Africa was a disaster; the wood was of such poor quality as to be unusable. This is the reason why a company like Glenmorangie pays such close attention to wood cultivation, to the point where Bill Lumsden, their whisky supremo, flies out to the United States to individually select the trees that’ll be used to make their casks; and why a brand like Glenfiddich celebrates the intricate role of the wood in its whisky – as evidenced by the beautiful “Journey of the Cask” photo essay, from which I’ve chosen images to accompany this piece. I’ll spare you a detailed knowledge the actual chemistry – because it’s above my pay grade I’ll admit, but also (I say somewhat conveniently) because it’s unnecessary if your objective is to better understand whisky for the purpose of its enjoyment. The basics of it though are as follows: The wood performs two functions. The charred or toasted inner layer, like the charcoal that it is, absorbs impurities from the raw spirit, making its smoother and more palatable. It also gives the spirit a pathway into the wood, from which it absorbs vanillins, lignins and tannins – the elements that make such a central contribution (the second function) to flavour.

Lost to this simplistic explanation are a multitude of other considerations, that all stake a claim: the seasoning of the wood – the process and time governing the drying of the cut wood (to be distinguished from the seasoning of the casks with liquid); the toasting and charring levels; the skill of the cooperage; the selection and proportion of virgin casks, first fills or refills; and, very importantly, the species of the wood – the most common being the Quercus Alba already mentioned, and Quercus Robur, the European oak. I had the privilege of attending a nosing with Edrington (Macallan, Highland Park) heavyweight Gordon Motion, during which we compared the same whisky matured for the same period in the same warehouse in American oak and European oak casks, both seasoned with the same sherry for the same period. From the number of times I’ve used the word same in that sentence you’ve obviously worked out by now that I’m setting you up. Yes, the whiskies were dramatically different.

Maturation then is a critical lever for flavour. Even today it retains a sense of that natural world mystique that must have astonished the first person to have stumbled upon it. Its influence on whisky is both broad and deep. It’s an easy trap to fall into though to think that it is all-important. Look at a whisky, nose a whisky, taste a whisky and the first thing that dominates your thinking is a consideration of the casks from which it’s made. As with all things that are imposing and extraordinary though, it’s worth taking a measured perspective to keep from being overawed. If I can leave you with only one guiding sentiment about maturation it’s this: appreciate it but don’t exaggerate it. Leave room for other things. May the dram be with you.